The use of solid state devices has been suggested for storing and for subsequent retrieval and reproduction of optical images as in a solid state camera. One such proposed system utilizes a miniaturized electronic camera and a magnetic disk or tape storage unit which can be packaged as a hand-held or shoulder-supported apparatus. The electronic camera utilizes a conventional charge-coupled device (CCD) imaging chip, the CCD thereon containing an array of pixels and the chip being located in the focal plane of the camera optics. The chip is exposed to the image and photocarriers are produced in each pixel. For reading the image, special electronic shifting circuits are used to shift the photocarriers on a line-by-line, and subsequently a pixel-by-pixel, basis to an output detector. The output detector signal is then stored on a video disk or video tape, for example, and the camera is then ready for the next imaging process. Because CCDs provide only very short term storage, the shifting process must begin substantially immediately after the image has been stored and must be completed within a relatively short time interval, i.e., one which is much less than one second if the quality of the image is to be preserved. If the shifting takes longer the quality of the image stored in the CCD device gradually diminishes and the image ultimately disappears.
Such an approach requires relatively elaborate electronic switching and shifting circuitry and the attachment of a magnetic recording device to the hand-held camera. According1y the device becomes relatively bulky and heavy and inconvenient to carry. As mentioned above, because the image that is stored in the CCD chip has a very short storage life, each image must be read out and stored in the magnetic recording device within a very short time after the chip has been exposed to the external image, in practice almost immediately, and the next image cannot be obtained until the overall switching, shifting and permanent storage recording process for a previous image has been completed.
In contrast it would be preferable to provide for solid state imaging in which images can be stored for much longer periods of time so that each image need not be accessed immediately for processing but rather many images can be stored in an array of solid state chips and then processed at a later time. Moreover, it would be desirable to avoid the need for an on-site magnetic storage device and for the elaborate electronic switching and shifting circuitry within the camera for reading out the image which has been formed and is to be stored. Currently there is no known solid state camera which provides such advantages.